Three new Ebola vaccines are being developed. An infectious disease expert explains – News
Recent developments in the fight against Ebola have brought a rare combination of positive news. Funding of up to US$62 million has been allocated to accelerate the creation of vaccines targeting the specific virus currently affecting Uganda and the Democratic Republic of the Congo (DRC).
Simultaneously, health authorities have revised the confirmed figures for the region. As of June 2, the DRC reported 344 confirmed cases and 60 related deaths, while Uganda reported 15 confirmed cases and one death, a significant shift from previous estimates of over 1,000 suspected cases.
The Challenge of Virus Variants
While approved vaccines like Ervebo and Zabdeno/Mvabea exist, they are designed specifically for the Zaire Ebola virus. They are not effective against the Bundibugyo Ebola virus currently circulating in the DRC and Uganda.
This discrepancy exists because different Ebola viruses possess different surface proteins. Because vaccines target these specific proteins, a new, dedicated vaccine is required to combat the Bundibugyo strain.
Three Primary Vaccine Candidates
The Coalition for Epidemic Preparedness Innovations is providing funding to fast-track three distinct candidates through clinical trials to ensure a safe and effective option becomes available as quickly as possible.
The IAVI Vaccine
Developed by the International AIDS Vaccine Initiative and the University of Texas Medical Branch, this single-dose candidate uses an approach similar to the Ervebo vaccine. While it has shown protection in macaque monkeys, human clinical trials are likely seven to nine months away.
The Moderna Vaccine
Utilizing mRNA technology similar to its COVID-19 and RSV vaccines, Moderna is targeting the surface glycoprotein of the Bundibugyo virus. Current funding is intended to support preclinical laboratory studies and human trials.
The University of Oxford Vaccine
Developed alongside the Serum Institute of India, this candidate uses technology similar to the Oxford/AstraZeneca COVID vaccine. While more animal data is needed, human trials could potentially begin within two to three months.
Obstacles to Control
The path to a fully controlled outbreak remains complex. Beyond scientific development, vaccines must receive regulatory approval, be manufactured at scale and be transported to the people who need them.
Recruiting volunteers for trials may be hindered by misinformation and negative perceptions of vaccination. This is particularly challenging for studies involving healthy volunteers in countries distant from the outbreak.
late-phase trials typically occur in the affected regions. These areas may be remote, lack healthcare resources, or be located in conflict zones, which could make it harder to prove safety and effectiveness.
Future Outlook
If successful, a single dose of a new vaccine could be suitable for those in direct contact with Ebola cases. For high-risk populations, such as front-line responders and healthcare workers, a two-dose regimen may be considered.
Until a vaccine is approved and deployed, basic infection control will remain the primary method for managing the current outbreak. However, a successful vaccine would likely serve as a critical tool for responding to any future Bundibugyo virus outbreaks.
Frequently Asked Questions
Why can’t existing Ebola vaccines be used for the current outbreak?
Existing vaccines like Ervebo and Zabdeno/Mvabea target the Zaire Ebola virus. Because the Bundibugyo virus has different surface proteins, these vaccines are not effective against it.
Which vaccine candidate is considered the most promising?
A World Health Organization (WHO) expert panel identified the IAVI vaccine, developed with the University of Texas Medical Branch, as the most promising candidate.
What factors make clinical trials difficult in these regions?
Trials are complicated by vaccine misinformation, the remote nature of affected areas, limited healthcare resources, and the presence of conflict zones.
How do you think global health organizations can better combat vaccine misinformation in remote regions?